Hey guys,
I just picked up an 86 RS with 305 T-5 "electronic" carb. My problem is the car running rough. after starting it a few times it will stay at idle (700rpm) or so, idle is rough but it stays running. as it gets warmer the idle improves,but only a litle smoother.
I have so far replaced the plugs,all filters including pcv, oil. I have also checked all wires for any arc's, verified correct timing. I am having a hard time tying to drain the tank, mech fuel pump?, I know the car sat for a few years, not sure how many. knowing that I got a siphon and drained as much gas as I could out the filler neck, guage stil reads full ( may be due to bad gas causing float to stick???. I put in five gallons of fresh 93 and two cans of octane booster.
after doing all of this it definetly runs better. the problem now is that while trying to drive , any time i attemt to give it gas it wants to die out until it reaches approx 3500 and four barrels kick in at WOT then it attempts to take off, still sputters and hesitates, but tries to go.
Just FYI I know my way around cars, but all of my experience in the past was with Mustangs. had a few of those as a kid, all carb cars with v-8's. (I know don't rib me too much)!!!
This car apparently has some sort of "electronic" carb???? It does have an o2 sensor and it does have all of the smog related BS that came stock. I have not modified the engine in any way, and it does not appear that the previous owner did either.
My goal is to get the car running and driving while I prep the 350 I just picked up. I need to know more about this carb and related issues in order to trouble shoot. Speaking from experience, I do not want to drain the pocket book just guessing wildly about what what be at fault.
any help is greatly appreciated.
thanks

 

Welcome aboard thirdgen.org.

Are you sure about you car's model? There wasn't an "RS" in '86. The base model was called a "sport coupe", but there weren't any badges that said that.

The "RS" came out in '88, and it had a "throttle body injection" unit instead of a carb. So, if your car is an RS, it has to be '88 or later, and won't have a carb.

You speak of 4 barrels and mechanical fuel pump, so that would indicate an '86 sport coupe.

Anyway, did you do anything with the distributor cap or rotor? The cap especially can cause rough running. How did you check the timing?

The octane boost didn't do anything for you, neither did the 93 octane. What you probably need is gasoling detergent, and after you add it, you'll probably need a new fuel filter.

Also check for leaking vacuum hoses or components.

The Carburetor forum has a lot of good information about this system. There is a sticky in the top section of that forum about "welcome to the carb forum", read that and especially the link about the computer carb. Your wide open throttle problem is probably a combination of a bad choke pull-off and improperly adjusted secondary air valve tension spring.These carbs really work well when properly set up and adjusted (often maladjusted by people who don't know what they're doing), so don't give up on it.

 

five7kid,
thanks. you are correct it is a sport coupe not and RS. I was not sure of designation.
checked the timing with timing light.
I am not to sure about the HEI distibutor set up??? never really got into one. does it have a typical cap and rotor assembly---have yet to take that off and look.
do you recommend a particular degergent?
no vacuum leaks--smoke tested.
I looked a little last night at the carb forum, i will look again trying to learn more about this carb set up.
thanks

 

When you check the timing, you have to disconnect a flat 4-wire connector that goes from the base of the distributor to the firewall harness. It isn't easy to find sometimes. If you don't disconnect that connector, your timing will be too retarded.

The HEI distributor through 1986 looked the same as 1975 on (use the same cap, rotor, and coil), except the computer type doesn't have a vacuum advance on it.

 

THAT is the reason I am here!!!! great info. thanks